// SPDX-FileCopyrightText: 2018 Stefan Majewsky <majewsky@gmx.net>
// SPDX-License-Identifier: Apache-2.0

package schwift

import (
	"net/http"
)

// Backend is the interface between Schwift and the libraries providing
// authentication for it. Each instance of Backend represents a particular Swift
// account.
type Backend interface {
	// EndpointURL returns the endpoint URL from the Keystone catalog for the
	// Swift account that this backend operates on. It should look like
	// `http://domain.tld/v1/AUTH_projectid/`. The trailing slash is required.
	EndpointURL() string
	// Clone returns a deep clone of this backend with the endpoint URL changed to
	// the given URL. This is used by Account.SwitchAccount().
	Clone(newEndpointURL string) Backend
	// Do executes the given HTTP request after adding to it the X-Auth-Token
	// header containing the backend's current Keystone (or Swift auth) token. If
	// the status code returned is 401, it shall attempt to acquire a new auth
	// token and restart the request with the new token.
	//
	// If the user has not supplied their own User-Agent string to the backend,
	// the backend should use the schwift.DefaultUserAgent constant instead.
	Do(req *http.Request) (*http.Response, error)
}

// DefaultUserAgent is the User-Agent string that Backend implementations should
// use if the user does not provide their own User-Agent string.
const DefaultUserAgent = "schwift/" + Version